The following text may have been generated by Optical Character Recognition, with varying degrees of accuracy. Reader beware!

THE MARINE RECORD. SHORT HAND METHOD TO FIND THE MAGNETIC FORCES OF A VESSEL. BY JOHN MAURICE, When the magnetic forces of a vessel are known the devia— tion for all courses can easily be found by graphical methods without swinging the ship. The question therefore is, how to find these forces without any cumbersome mathematical pro- cess. The solution of the problem without mathematics is necessarily confined to certain limits or points of the com- pass for which the deviation must be known. Such points are the quadrantal points. If the deviations for the four quad- rantal points are known the magnetic forces are known or can easily be found by the following rule: 1, Add together the deviation for all four points, the deviation for NW and SE with signs reversed, and take } of the alge- braic sum in degrees and divide it by 100. The result is in linear measure the value of the magnetic force from induced magnetism called G. 2, Add together the deviation for NE and SW the latter with sign reversed and call the result X. 8. Add together the deviation for SE and NW the latter with sign reversed, and call the result Y. 4, Add Y. to X. and divide the degrees by 161 plus 100 G, The result is the value of the component part of permanent magnetism acting in the direction of the ships keel, and is generally called B. 5. Add Y. with sign reversed to X. and divide the degrees by 161 plus 100 G. as before, the result is the value of the com- ponent part of permanent magnetism acting athwart-ships and is generally called C. Example.—Give the deviation as fol- lows: NE 24°10’, SW 10° 30’,SE6°0’, NW 19°30’. The sign minus indicates West deviation. Solution: 24° 10’ 24° 10’ GOO —10 30 10 30 19 30 -6 0 ee re 3 19 30 X =34° 40’ Y = 25° 30’ —_— X+tY= 60° 10 ae x ite = "5 —16 30 a a aes! RO ih as 27° 10” Teed B 27.2 X9= $2 % ‘ 20.4 = 100 G == = 005 = C .G=0. 204 181 The force G is constant; being little changed by lapse of time, therefore its yalue once ascertained may be used at fu- ture occasions. With G known, only the deviations for twe adjacent cardi- nal points are necessary to find B and © after the following rule: 1. Divide the deviation for E. or W., the latter with sign re- versed, by 57. The result is B. 2. Multiply the deviation for N. or S. the latter with sign reversed, by 1 minus G, and divide the product by 57. The result is C. Example:—Given the deviation for E. 19°, for North 4° 40/ and G = 0,18. Solution :— 19 57 The signs of B, and C, indicate in what quarter of the ves- sel the ship’s polar force is located in reference to the com- pass as will readily be seen from the following diagram: 4.7 X 0.82 57 B =0.33 C 0.07 3 S =a . RD +B +B -—c ec —~B -—B =—€ +C The intersection point of the two lines representing the com- pass center, This method enables vessels to find by repeated observatious of the deviation on two adjacent cardinal points the change in B. and C. and consequently the change in the deviation of all courses. N and § bearings are easily obtained by the pole star and E and W bearings by amplitudes extended into azimuths. An easy way to find the deviation for any course is also to place a compass on shore in the direction of the middle line of the ship and compare the course thus obtained with the course the vessel is headed on. In another article the graphical method for finding the devia- tion on all courses from the magnetic forces will be explained. ce Tue United States Treasury Department has issned a cir- cular to United States shipping commissioners looking toa strict enforcement of the laws against the employment of alien officers on vessels of the United States. MARINE DYNAMO AND ENGINE. UR ILLUSTRATION THIS WEEK SHOWS THE marine dynamo coupled to a double vertical engine designed especially for vesrel installations according to the strict requirements of the U. 8. Navy. The U. 8. cruisers Petrel, Vesuvius, Newark, Dolphin and Miantono- mah are fitted with this mechanism. The Thomson Houston Co. are the manufacturersof the marine dynamo and engineand it is learned that the best possible satisfaction is gained wherever their installations have been placed aboard ship, It would have been thought the suggestion of a lunatic but afew years ago. If a vessel-owner had been approached with a recommendation to place an electric light installation on board of his vessel, to the entire exclusion of oil. A gas plant placed in a South American passenger steamer only fifteen years ago was considered a wide departure, even pro- gressive vessel-owners questioning its advantage in point of service and economy, while to-day, the passenger steamer or wcdern steel freight steamer on the lakes would find it a posi- tive hardship to be without the electric installation, and, as we noted in these columns last week a contract has just been closed to equip a fleet of six large steel freight steamers owned in Cleveland with a complete electric light installation, Not only are these dynamo’s made by the Thomson Houston Co. for lighting purposes on board ship, but we find among their specialties a most compact and powerful electric hoisting engine for deck, wharf or warehouse facilities, also a marine search light made to swing in any direction and of 2,000 to 6,000 c. p. Those interested in building, managing, owning and sailing modern tonnage should be apprised of all of these advance- ments in their special line of business as it effects the ledger accounts where antiquated methods and mechanism are kept in use to compete with modern, speedy, reliable and economi- cal substitutes. In a word, those who are not up to theapirit of the times in technical pursuits, mechanical devices, and a trained experience of their class calling, are soon overstepped by others who are, and in so technical a following as the dis- tinct marine industry, a vessel, and what she can do, or what may be done with her, will always remain a paramount question to be successfully dealt with by men of experience and training, while novices may lose money for their owners with equanimity in their efforts to compete with skill and ex- perience, Sete NOMENCLATURE, The three new steel freight steamers designed by Manager E, T. Evans, of the Anchor Line, are named as follows: Co- dorus, Schnylkill and Mahoning. It will be recognized that the nomenclature is derived from Pennsylvania waterways, and are most appropriate for steamer names; they are also distinc- tive, easy sounding, and relate to geographicul certainties, as opposed to the evanescent fame of personality. These boats are being built respectively at the Union Dry Dock Co., Buft- alo, N. Y.; The Globe Iron Works Co,, Cleveland O., and the Detroit Dry Dock Co., Wyandotte Mich.;they will each carry about 3,000 tons, or 9,000 in all, and their approximate cost will be half a million dollars. It is already widelytudmitted that they will prove the most economical package freight carriers ever constructed on these waters, aud Manager Evans is quoted as closing a first-class contract for a well advanced type of mod- ern steel freight steamers, ei A. R, McKaw wants to handle all lake freight in and out of Chicago, The question is can he do it? THE FIRST OCEAN STEAMER. Much has been said and written regarding the priority steam navigation, A journal of American inventions and 4 dustries in treating of the history of steam navigation kindly forwards us advance sheets of the work, a notice of which is con- tained in another column of this issue and the following ex- tract is made to show the nature of the work and its original scope. “The first ocean steamship was built at Corlear’s Hook, New York, by Crocker & Fickett. She was 380 tons burthen, and — was launched August 22, 1818, to run between New York and — Liverpool as a sailing packet. About the time she launched, Captain Moses Rogers, then of Savannah, Ga., suggested to Messrs. Danning, Scarborough, Sturges, Burroughs, Henry, McKenna and others, the idea of constructing a steamer to run between Savannah and Liverpool. They accordingly pur- cbased this ship, and named her the Savannah. Her castin, were made in New York and her boiler at Elizabeth, N, J, She made her trial voyage to Savannah in April, 1819, and ar. rived there from New York in seven days. She had to take in her wheels several times and rely on her sails. She sailed — from Savannah for Liverpool, May 26, 1819, under the com- mand of Captain Rogers, of New London, Conn. Moses 1 ; 4 - ; ; H i i Rogers, his brother-in-law, was master and engineer, and third officer. In his report of the voyage, Mr. Rogers says: ‘‘We made the port of Liverpool in twenty-two days after leaving the port of Savannah; fourteen of the twenty-two under steam. The only reason why the whole voyage was not performed by steam was the fear of the fuel giving out. Off Cape Clear the Admiral at Cork despatched a ship to our relief supposing we were on fire. At Liverpool we caused a great deal of excitement, and suspicions of haying some designs to release Napoleon from St. — Helena. From Liverpool we proceeded to Copenhagen, and from thence to Stockholm. At both places the Savannah ex- cited great curiosity. Atthe latter place she was visited by the royal family, our Minister, Mr. Hughes, and Lord Lyn- © doch. The latter went with us to St. Petersburg. On the pas-— sage he desired us to bring the vessel from steam to canvas. He held his watch and noted the time, fifteen minutes. He was so delighted that he exclaimed, ‘I blame no man in the United | States for being proud of his country; and were I a young man I would go there myself.’ The Emperor of Russia came en board at Cronstadt, and was much pleased with the vessel, and presented Captain Rogers with two iron chairs.”” $< + ____ THE INSURANCE COMPANY OF NORTH AMERICA, OF PHILADELPHIA. This company haying been founded in 1792 has reached its” hundredth year, and its last statement shows it to be enjoying a vigorous old age. Its total assets are $9,278,220, of which a Mr. Blackman was in other first class securities. It has a capital of $3,000,000, a surplus over all liabilities of $2,225,475.31, and a reserve for reinsurance of $2,789,587.08. Its income during the year w: ‘$5,417.448.67, and its total expenditures were $4,624,559°89 The chief officers of the company are Charles Platt, presiden William A. Platt, vice president; Eugene L. Ellison, sec vice president; Greville E, Fryer, secretary and treasurer) John H. Atwood, assistant secretary; Catlin & Platt, neys and marine managers, Benoni Lockwood, fire mana; George L. McOurdy is manager of the lake marine dep ment, Chicago, Ills, —_ + re “f Masor E, H. Burrner, Corps of Engineers U. 8. As! now stationed at Buffalo, N. Y.